Welcome to the Environmental turbulence analysis littera Lab!

The Et al. lab focuses on understanding the role of fluid mechanics in environmental processes. We are particularly interested in turbulent transport between buildings, forest, costal vegetation, and particle/droplet laden flows. We employ and further develop experimental techniques to study turbulent flows in these complex geometries.

Et al. stands for Environmental turbulence analysis littera, which means the study of the effects of turbulence on environmental flows with careful and detailed experimentations and analysis to advance our design capabilities in engineering. The abbreviation et al. means and others and is often used to cite collaborative work in scientific journals. (Fun fact: do you know that the most cited “scientist” on Google Scholar is et al.?) The adoption of this name reflects our philosophy that science is a collaborative endeavor and benefits from different perspectives, viewing angles and inclusion.

### Physics of Turbulence

Turbulence is the most important unsolved problem of classical physics - Richard Feynman

## Chris CK Lai

### Assistant Professor

Experimental Fluid Mechanics, Turbulent Mixing and Transport, Turbulence Theory and Modeling

## Shantanu Soumya

### PhD student (Spring ‘20 - Present)

Fluid Mechanics, Environmental Fluid Mechanics, Multibody Turbulence, Experimental Fluid Dynamics

# Projects

#### Multibody turbulent flow

Production of turbulence in an array of spheres with relative motions– air-water flows.

#### Stratified turbulence

Mixing and scale interactions in stratified turbulence– improving turbulence models and estimates of oceanic mixing efficiency.

#### Turbulent flow in porous media

Turbulent-laminar flow transitions in porous media– solute transport in river and groundwater.

# Recent Publications

### Turbulence statistics in a negatively buoyant multiphase plume

In this paper we report an experimental study characterizing the turbulence inside a heavy particle plume descending under gravity within a salt–water solution.

### Mean velocity, spreading and entrainment characteristics of weak bubble plumes in unstratified and stationary water

In this paper we present an experimental and theoretical study of weak bubble plumes in unstratified and stationary water. We define a weak bubble plume as one that spreads slower than the linear rate of a classic plume.

### The turbulent kinetic energy budget in a bubble plume

We present the turbulent kinetic energy (t.k.e.) budget of a dilute bubble plume in its asymptotic state. The budget is derived from an experimental dataset of bubble plumes formed inside an unstratified water tank.

### Budgets of turbulent kinetic energy, Reynolds stresses, and dissipation in a turbulent round jet discharged into a stagnant ambient

This paper presents a set of stereoscopic particle image velocimetry (SPIV) measurements of a turbulent round water jet (jet exit Reynolds number $Re=2679$ and turbulent Reynolds number $Re_{T}=113$) discharged into an initially stationary ambient.

### Energy cascade in a homogeneous swarm of bubbles rising in a vertical channel

We perform direct numerical simulations (DNS) of millimeter-size air bubbles risingin a vertical water channel. Our objective is to …

# Teaching

#### CEE 6261. Environmental Fluid Mechanics. 3 Credit Hours.

Dynamics, mixing, and contaminant transport in surface water bodies, including lakes, rivers, estuaries, and coastal waters. Introduction to numerical models. Prediction of mixing zones.

#### CEE 6281. Open Channel Hydraulics. 3 Credit Hours.

Flow of liquids with free surfaces in artificial and natural channels. Analysis of flow resistance. Computation of gradually varied flow profiles. Flow through transitions, spillways, bridges, culverts. Analysis of unsteady flow.

# Lab News

### Upcoming Seminar at Johns Hopkins Center for Environmental and Applied Fluid Mechanics

Tune in to the virtual seminar https://wse.zoom.us/j/93762992307 this Friday (Feb. 26, 2021) 3 pm EST. Title: “Pseudo-Volumetric Reconstruction of Velocity and Density Fields from 2D Data & Energy Cascade in Multiphase Flows”

### Invited talk for this fall's Cornell Fluids Seminar

In this talk, I have presented the research from my on-going collaboration with colleagues in the Extreme Fluids Team at Los Alamos National Lab. The abstract for this talk is below:

### Awarded Small Bets Seed Grant 2020!

The project Like a knife through butter- glacial melt by ocean plumes investigated in novel laboratory experiments has been awarded the Small Bets Seed Grant 2020. This is a collaboration with Dr.

#### School of Civil and Environmental Enginnering at Georgia Tech

Nov 2019 – Present

# Contact

• chrislck@gatech.edu
• Mason Building, 790 Atlantic Dr, Atlanta, GA 30332
• Chris Lai’s office is at Mason 2223